Last week, I called a friend for a big birthday—one of those pesky decade markers—and she wondered whether she had to stop all silliness, now that she’s reached an age of gravitas.

I argued to the contrary: Knowing yourself can easily go down as one of the biggest benefits of getting older. And sometimes, knowing yourself means admitting goofiness. (At least, it does for me.)

Besides, we decided, numerical ages—decades or no—don’t count as milestones requiring seismic mental and behavioral shifts. Yes, the years advance, bringing physical and psychological changes. Yet specific numbers have less validity than how we feel, which can vary widely no matter our chronological ages.

And so what, we mused, count as actual milestones? After all, careers, jobs, growing up, growing older, goals, friendships, romantic relationships, and more all have milestones.

Milestones mark progress.

My friend and I met while traveling, but many people would consider the first tandem vacation a milestone in friendship—one some people wouldn’t even attempt to reach—and travel definitely marks progress in a romantic relationship—one that could even call a halt to further progression.

Some of my most vivid memories mark my turn toward adulthood: The moments that taught me parents aren’t infallible, pedestal-vaulted gods but simply people. My first car accident, which happened in a distant city before the era of cell phones and the Internet. The latter experience launched me on a lifetime of confident self-reliance. The former lessons freed me to show my parents more compassion.

In careers and jobs, people mention the first time they managed someone in a task or as a direct report. Some talk about the first time they oversaw a full project with budget responsibility. And many people mark ninety-day, year, and five-year tenures.

And everyone ever in a romantic relationship will hark meeting the family as a big milestone. My friend—the one with the birthday—said you never really know about a man’s long-term potential until you’ve seen how he behaves when sick. Personally, I think you have to see how someone fights to know about a possible future together.

Seems like, in life, milestones abound. And so, curious, I’ll take a poll:

What do you consider your big milestones in life so far?